With the rapid development of technology and products of printed circuit boards (PCBs), the demand for carbide drills increases year and year, new carbide drills appear ceaselessly, and requirements for carbide drills become higher and higher. A carbide drill for PCBs (referred to as “PCB micro-drill”) is a microporous machining tool in a complex shape and with spiral slots, and is derived from a traditional twist drill. The size of a PCB micro-drill is small, and the structure of a distal end of the drill needs to be clearly observed by means of an optical microscope. Currently, most PCB manufacturers use CNC drilling machines to process PCBs, wherein a CNC drilling process is an important step of a PCB manufacturing process, and a carbide drill is a key factor to decide the quality and efficiency of the drilling process.
An existing miniature drill mainly makes its two spiral slots intersect by changing their helix angles, wherein one method is to increase the helix angles to make the two slots intersect, and another method is to reduce the helix angles to make the two slots intersect. After the two slots intersect, the slots may stop or go in parallel from the intersection place. The main characteristic of these two intersection methods is that the two spiral slots intersect near the drill tip or the drill body, but which may cause a problem that: the centroid of the drill tip near the intersection portion of the spiral slots of the drill tip is offset; when the drill rotates at a high speed, the drill tip will swing violently due to the deviation of the centroid from the rotation axis, which may seriously affect the position accuracy of the drilled holes and the anti-break performance during drilling.